Analysis of heart, lung and vascular disorders by means of noninvasive auscultation has long been a very useful tool for medical diagnosis of ailments. Conventional electronic stethoscopes had not been invented until the Year 1922. Modern electronic stethoscopes can improve sound quality and provide a visual indication of heart sounds or chest sounds, such as cardiophonography. However, early electronic stethoscopes, which are composed of vacuum tubes or transistors, were typically more expensive and bulkier than conventional stethoscopes. Accordingly, electronic stethoscopes can only begin to replace the dominant role of conventional stethoscopes after the rapid development of IC technology at the end of 20th century. Nevertheless, there were many electronic stethoscopes currently available on the market, which can be divided into two categories, i.e. the analog electronic stethoscopes and the digital electronic stethoscope, whereas most of which are analog electronic stethoscopes.
Compared with conventional stethoscopes, the electronic stethoscope, despite its advantages, and disadvantageous, is more expensive and requires certain practice for those who have been accustomed to the operation of conventional stethoscopes, and moreover, its operation is often limited by its battery capacity and thus requires a battery change from time to time. Accordingly, although it is becoming popular nowadays, the electronic stethoscope still can not replace the conventional stethoscope completely.
In a prior-art auscultation device disclosed in U.S. Pub. No. 4,534,058, entitled “Electronic stethoscope with automatic power shut-off”, the electronic stethoscope is designed with a shut-off circuit that enables the stethoscope to shut off and enter a power-saving mode after the stethoscope is detected to be inactive for a specific period of time. The aforesaid automatic power shut-off is already common in most conventional electronic stethoscope currently available on the market, however it has shortcomings listed as follows:                (1) Any electronic stethoscope with automatic power shut-off will have to wait for the specific period of time until it can be shut off and can not be shut off immediately after it is inactive such that there is power being wasted during the waiting.        (2) The operation of a conventional electronic stethoscope is limited by its battery capacity and thus requires a battery change from time to time so as to prevent the battery from running out in the middle of an auscultation process.        (3) Any electronic stethoscope that requires constant battery change so as to sustain a normal operation is not only costly, but also is not environmental friendly.        (4) Any medical personnel who wants to use the aforesaid electronic stethoscope with such automatic power shut-off that is inactive will have to start it by pressing a button or a switch which is inconvenient and time-consuming.        
Therefore, there is a need for an electronic stethoscope that is designed with environmental protection and energy-conservation capabilities for reducing power consumption while prolonging the lifespan of the battery used in the apparatus.